Mitigation of arsenate toxicity by indole-3-acetic acid in brinjal roots: Plausible association with endogenous hydrogen peroxide

The role of indole-3-acetic acid (IAA) and hydrogen peroxide (H2O2) crosstalk in regulating metal stress is still less known. Herein, role of IAA in alleviating arsenate (As-V) toxicity in brinjal seedlings along with its probable relation with endogenous H2O2 was investigated. Arsenate hampered root growth due to greater accumulation of As and decrease in phosphorus uptake that resulted into inhibited photosynthesis and cell death. Further, As-V induced oxidative stress markers and damage to macromolecules (lipids and proteins) due to alterations in redox status of glutathione as a result of inhibition in activity of glutathione synthetase and glutathione reductase. However, application of IAA with As-V improved root growth by significantly declining As accumulation and oxidative stress markers, sequestrating As into vacuoles, and improving redox status of glutathione which collectively protected roots from cell death. Interestingly, addition of diphenylene iodonium (DPI, an inhibitor of NADPH oxidase) further increased As-V toxicity even in the presence of IAA. However, application of H2O2 rescued negative effect of DPI. Overall, the results suggested that in IAA-mediated mitigation of As-V toxicity in brinjal roots, endogenous H2O2 might have acted as a downstream signal.